I forgot to add the Exposed file. Oops.

Data/Profunctor/Exposed.hs

@@ -0,0 +1,26 @@
+{-# LANGUAGE FunctionalDependencies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{- |
+Module      :  Data.Profunctor.Exposed
+Description :  Exposes Kleisli category structure beneath a profunctor.
+Copyright   :  (c) Paweł Nowak
+License     :  MIT
+
+Maintainer  :  Paweł Nowak <pawel834@gmail.com>
+Stability   :  experimental
+-}
+module Data.Profunctor.Exposed where
+
+import Data.Profunctor
+
+-- | Exposes structure of a Kleisli category beneath a profunctor.
+-- 
+-- Should obey laws:
+-- 
+-- > merge . rmap return = id
+-- > lmap return . expose = id
+-- > rmap (>>= f) = merge . rmap (fmap f)
+-- > lmap (fmap f) . expose = expose . lmap f
+class (Monad m, Profunctor p) => Exposed m p | p -> m where
+    expose :: p a b -> p (m a) b
+    merge  :: p a (m b) -> p a b